Plant Milkweed for the Monarch Butterfly

Each fall, hundreds of millions of monarch butterflies migrate from Canada and the United States, to central Mexico, to wait out the unfavourable conditions of northern winters. Each spring, they begin the migration north and need milkweed for food along the way. Milkweed is an important source of nutrients during the migration but is also imperative for the monarch larvae to develop fully into a butterfly. The monarch needs your help, so please plant some milkweed in your garden.

Milkweed is the main food of choice for the monarch butterfly. In fact, it is almost their only food.  Unfortunately due to eradication of invasive milkweed, extended agriculture lands and urbanization the extensive belts of milkweed, once common to North America and imperative to the Monarch, are disappearing. In the past, milkweed was used by Aboriginals for its medicinal qualities, healing lung problems and baby umbilical cord sites as well as used as a diuretic, to cause vomiting or for deworming.

Milkweed is a perennial plant that will grow very well in the Rainy River District. The two varieties of milkweed that will grow here are common and swamp. Milkweed is a great plant for areas that have poor soil as they will tolerate dry and infertile conditions, although fertile garden soil produces the best plants. Milkweed spreads by seeds that are windborne and via underground rhizomes. The rhizomes of common milkweed are the most aggressive causing it to become invasive even though it is a native species to North America.

Common milkweed has broad, oblong leaves; flowers of varying shades of pink; and grows about one to one-half metres tall. Flowers emerge in mid-summer. Gardening Guru Tip: As common milkweed is very invasive, prevent it from becoming invasive in your garden by planting it in a large container and bury the container so the lip is even with the soil. Another alternative is to choose to not plant it at all as there are other less invasive varieties available.

This little monarch caterpillar will one day bloom into a beautiful butterfly, but until then it will subsist almost entirely on varieties of the milkweed plant. You can help monarch butterfly populations by planting milkweed in your own garden, giving caterpillars a much needed energy boost as they prepare for their spectacular metamorphosis. – Vicki Jewell photo

Swamp milkweed grows about one to two metres tall and has very with fragrant, showy clusters of flowers in a white, pink or light purple. It has long, narrow, lance-shaped leaves found in pairs on the stem. Swamp milkweed does well in landscape plantings with moist soil and in plantings near water but will also tolerate difficult locations such as heavy clay, dry and infertile soils. Swamp milkweed is not invasive like common milkweed so it can be planted directly into the soil. Best of all, it is as attractive to egg-laying monarchs as common milkweed. Another bonus of planting the swamp variety of milkweed, is that it has very bitter leaves that are very deer and livestock resistant. Gardening Guru Tip: if you want to establish milkweed in your garden, plant swamp variety over common variety. Swamp milkweed (cultivars ‘Ice Ballet’ and ‘Cinderella’) has been available at the local nurseries in the past.

To propagate your own plants from seed, collect seeds in the fall, when the brown pods have dried and begun to split. Crack the pods open completely allowing the seeds to dry for one to two weeks in paper bags. Several weevil larvae prey on developing seeds, so look for signs of damage including small entry holes in the pod exuding latex. Throw the infested pods away. Once they are dry, place the seeds into plastic bags filled with moist perlite or vermiculite and store them in a cold place, approximately two to five degrees Celsius, for at least four to twelve weeks for a stratification period. Plant the seeds in the early spring, along with your other seeds, following the same process as for starting any other seeds. Place your newly sown seeds in a well lit area once planted, as they need light for germination. Allow four to eight weeks of inside growing (they should have a set of true leaves by this time) before transplanting outside after the danger of frost has passed.

To plant some milkweed in your own garden, look for it at your local nursery. It is extremely rewarding to have the monarch come and lay eggs on your milkweed and then develop into caterpillars. The caterpillars are extremely hungry and can impressively eat a whole plant in less than forty-eight hours but don’t worry, as your plant will spout new leaves and will be there again for the next generation of monarch.